//将两个升序链表合并为一个新的 升序 链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。
//
//
//
// 示例 1：
//
//
//输入：l1 = [1,2,4], l2 = [1,3,4]
//输出：[1,1,2,3,4,4]
//
//
// 示例 2：
//
//
//输入：l1 = [], l2 = []
//输出：[]
//
//
// 示例 3：
//
//
//输入：l1 = [], l2 = [0]
//输出：[0]
//
//
//
//
// 提示：
//
//
// 两个链表的节点数目范围是 [0, 50]
// -100 <= Node.val <= 100
// l1 和 l2 均按 非递减顺序 排列
//
// Related Topics 递归 链表 👍 1883 👎 0

package leetcode.editor.cn.hot100.finished;
/**
 * @author lucas9
 */
public class 合并两个有序链表 {
    public static void main(String[] args) {
        Solution solution = new 合并两个有序链表().new Solution();
        // DO TEST
    }
    public static class ListNode {
        int val;
        ListNode next;
        ListNode() {}
        ListNode(int val) { this.val = val; }
        ListNode(int val, ListNode next) { this.val = val; this.next = next; }
    }
    //leetcode submit region begin(Prohibit modification and deletion)
    /**
     * Definition for singly-linked list.
     * public class ListNode {
     *     int val;
     *     ListNode next;
     *     ListNode() {}
     *     ListNode(int val) { this.val = val; }
     *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
     * }
     */
    class Solution {
        public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
            if (null == l1) {
                return l2;
            }
            if (null == l2) {
                return l1;
            }
            ListNode head, ans;
            if (l1.val < l2.val) {
                ans = head = l1;
                l1 = l1.next;
            } else {
                ans = head = l2;
                l2 = l2.next;
            }
            while (null != l1 && null != l2) {
                if (l1.val < l2.val) {
                    head.next = l1;
                    head = head.next;
                    l1 = l1.next;
                } else {
                    head.next = l2;
                    head = head.next;
                    l2 = l2.next;
                }
            }
            while (null != l1) {
                head.next = l1;
                head = head.next;
                l1 = l1.next;
            }
            while (null != l2) {
                head.next = l2;
                head = head.next;
                l2 = l2.next;
            }
            return ans;
        }
    }
    //leetcode submit region end(Prohibit modification and deletion)

}
